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Biomedical subjects

J Petit

Publications and source records attributed to J Petit.

At least 127 records · Page 7Linked to original sources
PubMed1993

Metabolic effects of propofol and flunitrazepam given for sedation after aortic surgery.

Sixteen patients who had undergone abdominal aortic surgery were allocated randomly to receive either propofol (total dose 3.2 (SEM 0.3) mg kg-1 h-1) or flunitrazepam (total dose 15 (2) micrograms kg-1 h-1) for 16 h after operation. Metabolic effects of sedation were assessed using a Deltatrac metabolic monitor. Initiation of sedation induced a 25% decrease in VO2 in both groups. The decrease was about 40% at 16 h. VO2 increased within 30 min after discontinuation of propofol and stabilized at values considerably less than the immediate postoperative value. A similar but slower increase was noted with flunitrazepam. While the propofol loading dose reduced the Buffington index and should therefore be avoided, no cardiovascular side effects were noted with the maintenance infusion. Weaning from ventilatory support was achieved within 15 (2) min and 264 (108) min after discontinuation of propofol and flunitrazepam, respectively.

Aortic Aneurysm, Abdominal↗
PubMed1993

Incidence of non-driving excitation of Ia afferents during ramp frequency stimulation of static gamma-axons in cat hindlimbs.

1. The aim of this investigation was to identify static gamma-axons which do not drive any Ia afferents at any stimulus frequency in any spindle which they supply, and to determine their occurrence in various hindlimb muscles (peroneus tertius, brevis, longus and tenuissimus). 2. Ia responses to static gamma stimulation were classified as 'non-driven' when the discharge did not follow the stimulation frequency, or its subharmonics, at any time during a linear increase in stimulus frequency up to 150 Hz lasting 2-3 s, and when tested at two muscle lengths--except in the tenuissimus muscle. In almost all experiments, cross-correlograms were used in addition to evaluate the percentage of these 'non-driven' responses in which a time-locking of discharge to stimulus pulses was obscured by irregularity of the Ia discharge. 3. In 104 spindles, out of 347 responses to stimulation of single static gamma-axons 332 (93%) could be characterized, and of these, 57% (183) were of the non-driven type. The mean number of static gamma effects characterized per spindle was 4.1 (fourteen experiments). In the large majority of spindles (79%, 82 out of 104) at least one response was of the non-driven type. 4. Of the static gamma-axons studied 16% were called 'non driving' ('ndr' gamma s-axons) because they elicited non-driven effects, and since they had the same qualitative effect consistently in all spindles whose discharge was modulated by stimulating them they were called specific 'ndr' axons. If axons with non-driven effects, but acting on one spindle were included in the 'non-driving' category the proportion was 23%. Of spindles tested 63% were innervated by at least one 'ndr' axon. 5. Absence of Ia driving during ramp frequency stimulation of gamma s-axons has been equated with selective bag2 contraction. All the non-driven responses identified in this study cannot be attributed to exclusive bag2 involvement because the total number of 'ndr' responses was too high. In fact, in the isolated spindle preparation bag2 and chain co-contraction were shown to elicit non-driven responses, so chain contraction is not detected reliably in all experimental conditions. Possibly chain fibre contraction is sometimes too weak to dominate the response, or can be of a non-driving character.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Properties of motor units after immobilization of cat peroneus longus muscle.

Changes in contractile properties of cat peroneus longus motor units were studied 2, 5, and 8 wk after selective immobilization of this muscle, which was achieved by fixing the distal tendon of the peroneus longus to the fibula either at the muscle minimal physiological length ("short" length) or at the length for a 90 degree ankle joint ("neutral" length). In each muscle, 75-90% of the units [slow (S), fast resistant to fatigue (FR), fast intermediate (FI), and fast fatigable (FF)] were studied. Immobilization elicited a permanent decrease in tetanic force developed by single motor units, which was larger for resistant-to-fatigue units (S, FR). In most instances this decrease was not related to the immobilization length. In all units, twitch contraction and half-relaxation times underwent a transient increase, the extent and time course of which were influenced by immobilization length. The relationship between the frequency of motor units activation and the ratio of unfused to maximal tetanic force was studied. For fast units, there was a transient shift of the relation toward low frequencies after 2 and 5 wk of immobilization at neutral and short length, respectively.

Animals↗
PubMed1993

Effects of immobilizing the cat peroneus longus muscle on the activity of its own spindles.

The peroneus longus muscle of 10 cats were immobilized by fixating the distal tendon on the fibula at one of two length: neutral (length for a 90 degrees flexion of the ankle joint; 5 cats) or short (length for a full extension of the joint; 5 cats). Spindle afferent discharges were studied after 2 (4 cats) or 5 wk (6 cats) of immobilization and compared with those of four control animals. In each muscle, the discharges of nearly all primary and one of secondary muscle spindle endings were recorded during 2-mm ramp-and-hold stretches applied at different initial muscle lengths. A very slight increase in both the static discharge and the dynamic index of primary endings was observed in passive spindles. The increase in connective tissue that occurs in immobilized muscle and reduces muscle compliance was likely the sole alteration responsible for this constant effect. The responses to stretches of primary endings during stimulation of static and dynamic gamma-axons were not altered. Muscle immobilization at short length, even if spindle properties are not altered, can be expected to reduce the overall amount of group Ia afferent impulses with possible long-term changes on motoneuron properties.

Animals↗
PubMed1993

Maximum shortening speed of motor units of various types in cat lumbrical muscles.

1. Isotonic shortening of cat superficial lumbrical muscles was studied during maximal tetanic contractions of single motor units of identified types. For each motor unit, the maximal speed of contraction, Vmax, was determined by extrapolating to zero the hyperbolic relation between applied tension and speed of shortening. 2. The maximal speeds of shortening of motor units formed a continuum with the highest velocities observed for the fast fatigable motor units and the lowest for the slow motor units. 3. On average, the maximum speed of shortening increased with the tetanic tension developed by the motor units. 4. In motor units with isometric twitch contraction times less than 35 ms, these times showed a significant inverse correlation with Vmax. Progressively longer contraction times were associated with rather small changes in Vmax. 5. The implications of these findings on the speed of muscle shortening during motor-unit recruitment are discussed.

Animals↗
PubMed1993

[Atresia or congenital stenosis of the left coronary ostium. Myocardial revascularization in 5 children].

Five patients, 3 months to 13 year old with atresia (4) or stenosis (1) of the left coronary artery underwent myocardial revascularisation at Marie Lannelongue Hospital. The preoperative symptoms were dominated in one case by cardiac failure due to myocardial infarction and in the other cases by effort angina with syncope. The operative technique of revascularisation in one case was angioplasty with enlargement of the left main coronary artery with a patch and, in the others, bypass graft of the left coronary artery with the left internal mammary artery. All 5 patients survived surgery and are asymptomatic with a follow-up of 6 months to 7 years. Control coronary angiography confirmed the patency of the different procedures of myocardial revascularisation. In 3 children, exercise electrocardiography was normal. Myocardial revascularisation of a child with a congenital stenotic abnormality of the left coronary network is possible, the technique of which depends on the diameter of the left main stenosis when the vessel is absent or atresic, left internal mammary artery bypass graft is the only solution. When the left main coronary is stenosed but patent, direct reconstructive surgery is an interesting alternative.

Adolescent↗
PubMed1993

[Comparison of long-term results of arterial switch and Senning procedure in transposition of great vessels with intact ventricular septum].

One hundred and five survivors after the 30th day of complete cure of transposition of the great arteries with intact ventricular septum between 1980 and 1985 were followed up. Fifty-four had an arterial switch (AS) in a single stage at an average age of 10 +/- 9 days and 51 had Senning's procedure (S) at an average age of 4 +/- 2.5 months. The average follow-up (97% of patients) was 5.8 +/- 1.1 years for the AS group and 9.3 +/- 2.3 years for the S group. The actuarial survival at 5 years was 100% in the AS group and 85.8% in the S group (p < 0.01) (8 late deaths). In the AS group, 3 patients were reoperated for stenosis of the pulmonary artery and, in the S group, 4 patients underwent 6 reoperations. All but 3 patients in the S group and all but 1 patient in the AS group are in functional Class I of the NYHA classification. Doppler echocardiographic studies have shown mild to severe dysfunction of the systemic ventricle in 2% of the AS group and 26% of the S group (p < 0.001). Holter monitoring, performed in 70% of patients in the S group showed sinus node dysfunction in 60% and sinus rhythm in 40% of cases. In conclusion, good functional results were observed at over 5 years in both groups. However, the absence of late mortality and the minimal incidence of systemic ventricular dysfunction in the AS group confirm the authors' choice of indication of arterial switch for the treatment of transposition of the great arteries with intact ventricular septum.

Actuarial Analysis↗
PubMed1993

[Intravenous leiomyomatosis of the inferior vena cava and the right heart atrium. Apropos of a case and review of the literature].

The authors report a case of intravenous leiomyomatosis, a rare uterine tumor, extending to the inferior vena cava and to the right atrium. It seems to be the first case described in France. The wrong diagnosis of massive pulmonary embolism and the distance from a cardiac surgery unit led to emergency tumorectomy without cardiopulmonary bypass. A review of the literature studied the 24 cases with cardiac extension already reported, 19 operated and 5 autopsy reports. Right cardiac failure or syncopes are the most frequent clinical signs. Sometimes histologic examination after hysterectomy leads to the diagnosis. Echocardiography diagnoses an intra-atrial mass. Abdominal ultrasonography and phlebocavography show the iliocaval portion of the tumor. Cardiac angiography and computed tomography are also contributive. Surgical treatment except in extreme conditions should be performed by a cardiac surgical team. If the diagnosis of intra-venoux leiomyomatosis has been made preoperatively a one-stage cardiac and abdominal treatment should be preferred. In the other cases, cardiac surgery should be done first, allowing a precise histologic diagnosis and subsequent treatment of the iliocaval and uterine lesions.

Echocardiography↗
PubMed1993

[Burgeoning form of cancer of the superior biliary bifurcation Nosological, diagnostic and therapeutic aspects. Apropos of a case].

The authors report a case of fungating cholangiocarcinoma of the porta hepatis, revealed by jaundice in a 73-year-old cholecystectomized female. The diagnosis of obstruction of the hepatic duct junction suspected by ultrasonography and computed tomography was confirmed intraoperatively. Disobstruction was followed by laterolateral choledocoduodenostomy. An early recurrence required a second disobstruction with surgical then endoscopic insertion of a drain, with 23 months of satisfactory survival. The discussion is focused on hilar fungating cholangiocarcinoma. The extrahepatic (Klatskin tumor) or intrahepatic origin of these lesions, the circumstances and morphological investigations for the diagnosis are discussed. Particularities of the treatment are mentioned, with emphasis on the possible participation of the endoscopist for choledocho or hepaticoduodenostomy.

Adenoma, Bile Duct↗
PubMed1992

[Criteria for choice of the donor in heart transplantation in adults].

Among 66 consecutive adult heart transplant recipients operated on from January 1988 to October 1991, 11 experimented early graft dysfunction (4 of them died). Mean donor's age was 37.4 +/- 11 years; 9 patients were older than 50 years; 85 percent of donors received dopamine. Were found without any significant influence on early graft function: donor's age, weight mismatch, duration of donor's intensive care, dose of dopamine administered, external cardiac massage and relative hemodynamic instability, and ischemic time. Conversely, a history of chronic alcoholism in the donor is of pejorative significance, which is not without consequences in view of the current scarcity of donors.

Adult↗
PubMed1992

[Neonatal heart transplantation. First results].

Two 5- and 17-days old neonates with hypoplastic left heart syndrome respectively underwent orthotopic heart transplantation. The donor-recipient weight ratio was +58 percent and +88 percent; ischemic time was 144 and 167 min. The immunosuppressive protocol included thymoglobulin during the induction period and a classical 3-drug therapy, with a rapid tapering off of prednisone over 3 weeks. No infectious complication was observed; each infant experimented one episode of acute rejection, successfully treated with prednisolone. Forty-three months and 10 months later, the 2 children are doing well, with normal renal function and normal growth. No late rejection episode was observed. Heart transplantation in neonates is feasible, the short-term and mid-term results are good. Despite important ethical problems, heart transplantation represents a great hope for neonates with inoperable congenital heart defects.

Graft Rejection↗
PubMed1992

Measurement of trazodone in plasma and brain of rat by capillary gas chromatography with a nitrogen-selective detector.

A specific and highly sensitive method for the measurement of trazodone in plasma and brain of rat is presented. The compound and the internal standard were extracted from alkalinized samples with hexane and analysed by capillary gas chromatography with nitrogen-selective detection. The method was demonstrated to be accurate and precise. The limits of determination were 2 ng/ml for plasma and 24 ng/g for brain, which makes this procedure suitable for pharmacokinetic analysis.

Animals↗
PubMed1992

Comparison of skeleto-fusimotor innervation in cat peroneus brevis and peroneus tertius muscles.

1. The skeleto-fusimotor or beta innervation was compared in cat peroneus brevis and peroneus tertius muscles, which differ in their composition of fatigue-resistant motor units; the slow (S) units predominate in brevis and the fast units (FR) in tertius. 2. In four brevis muscles, of thirty-four beta-axons (from a total of 114 axons supplying extrafusal muscle fibres) twenty-nine were dynamic (beta D) and only five static (beta S). In contrast, in three tertius muscles, of twenty-five beta-axons (from a total of 82 axons) twelve were static and thirteen dynamic. 3. In a population of thirty-five brevis and thirty tertius spindles, the proportion of beta D-innervated spindles was greater in the brevis (68.5%) than in the tertius (50%) whereas that of beta S-innervated spindles was greater in the tertius (40%) than in the brevis (17.1%). In a population of thirty-two brevis and twenty-seven tertius spindles in which the presence of bag1 fibres was deduced from the existence of a dynamic innervation, the proportion of spindles innervated by beta D-axons was 80% in the brevis and 62% in the tertius. 4. In both muscles, the number of beta D effects was greater than that of beta S effects. beta S-axons were rarely found to supply more than one spindle whereas beta D-axons supplying more than one spindle (up to four) were common. Spindles were often coinnervated by beta D- and beta S-axons.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1992

Early palliation of univentricular hearts with subaortic stenosis and ventriculoarterial discordance. The arterial switch option.

The optimal Fontan-type operation greatly depends on appropriate initial palliation. Several surgical techniques have been used in infancy to palliate patients with univentricular hearts, ventriculoarterial discordance, and subaortic stenosis. The two most common are pulmonary artery banding and Damus-Norwood procedures. Palliative arterial switch operation is another surgical option that was used in this early series of seven infants. The principle of this operation is to "switch" the subaortic obstruction into a subpulmonary obstruction; the coronary artery relocation on the large pulmonary trunk creates a harmonious aortic root and the connection of the rudimentary ventricular chamber to the pulmonary artery trunk creates a natural protection of the pulmonary vascular bed through the restrictive bulboventricular foramen. Seven infants with univentricular hearts, ventriculoarterial discordance, and subaortic stenosis underwent a palliative arterial switch operation. All infants had an associated aortic arch obstruction of various degrees, including one with interrupted aortic arch, five with coarctation with severe arch hypoplasia, and one with isolated arch hypoplasia. There were three with double-inlet left ventricle, three with tricuspid atresia, and one with transposition of the great arteries with ventricular septal defect and severe right ventricular hypoplasia. The subaortic obstruction was patent at birth in five patients who underwent a palliative switch operation in the first 2 months of life, and rapidly occurred following a previous neonatal pulmonary artery banding associated with arch repair in two patients who underwent a switch operation at 5 and 8 months of age, respectively. The operation includes aortic arch repair without prosthetic material, an atrial septectomy, and the arterial switch. An associated pulmonary shunt was required in five patients and a pulmonary artery banding in one. There was one early death in a patient with [S,L,L] anatomy and congenital atrioventricular block, leading to an early mortality of 14% (95% confidence limits: 1% to 28%). There was one late death. Four survivors are waiting for a Fontan-type procedure, and one survivor had satisfactory right ventricular growth. Early palliative arterial switch operation offers several advantages: reconstruction of a harmonious aortic root, natural protection of the pulmonary bed through the restrictive bulboventricular foramen, prevention of deleterious myocardial hypertrophy, and arch reconstruction without the introduction of a foreign material. This aggressive technique may provide a satisfactory palliation in infants with univentricular hearts and ventriculoarterial discordance, when the bulboventricular foramen/aortic anulus ratio is less than 0.8 or when the subaortic stenosis is severe enough to be associated with an arch obstruction.(ABSTRACT TRUNCATED AT 400 WORDS)

Abnormalities, Multiple↗